In constructing and replacing underground piping systems, such as manholes and sewer systems, relatively large pipes are needed, such as reinforced or non-reinforced concrete pipes and manhole risers. Such pipes are generally available in various predetermined lengths, but often a pipe is too long for a particular usage and must be cut to an appropriate size. The pipes, however must be able to fit together with other pipes forming closely fitting pipe joints and an interconnected system of pipes. In order to fit with another pipe, a spigot is formed at the end of one pipe which has been cut and mates with a corresponding bell end of another pipe.
Spigots are generally molded into a pipe but can also be formed by machining the end of a pipe, such as by grinding or milling. However, many grinding machines are expensive, difficult to operate, or incapable of grinding large concrete pipes. Other grinding machines fail to grind a spigot accurately with the necessary roundness and required tolerances. Additionally, prior art grinding machines are not easily adjustable for various diameter pipes often used on any one given job. Thus, prior grinding machines have not provided a simple, economic and accurate way of forming spigots in the ends of large pipes which have been cut to size.
Accordingly, what is needed is a method and apparatus for grinding a surface of a pipe to form, for example, a spigot whereby the spigot can be accurately and easily formed by supporting the pipe on the surface which is being ground. Furthermore, such a grinding apparatus should rotatably support the pipe by resting the pipe on support rollers positioned generally beneath the pipe without the need for complex workpiece support and rotation mechanisms and without the need to adjust the support rollers for various diameter pipes.